Thread-cutting machine



Sept. 27, 1949. ac. MACK THREAD CUTTING MACHINE 2 Sheets-Sheet 1 Filed July 9, 1945 INVENTOR .JTANLEY c. HACK ATTORNEYS.

Sept. 27, 1949. s, Q M 2,482,786

THREAD CUTTING MACHINE Mil/EN 70R JTA/VLET 6. NAM

ATTORAM'YJ.

Patented Sept. 27, 1949 Stanley 0. Mack, Clevelahdg 'Ohio; assignor to Merit Machine Company; Northfield. Ohio; a

corporation of Ohio equipped with my device;

Application July 9, 1945f;.sera .No..603,819

2 Claims. ((21; 25)' This invention relates to improvements in a lathe attachment which is particularly useful in the cutting of threads.

One of the objects of the presentinvention is to provide means associated with the tool rest of a lathe or the like adapted to hold the tool into engagement with the work up to a' predetermined point at which time the tool is suddenly moved awayfrom the work so as to end a tool out exactly at a predetermined point. It is possible with this device to make progressively deeper cuts andfltowithdraw the tool at exactly the same point. every time and to thereby produce a resultnot heretofore possible to my knowledge.

Another. object of the present invention is to provide. adevice as described above together with means for resetting thedevice after each cut by means of a very simple manual'operation.

Other objects and advantages of the invention are disclosed in the particular arrangement of coacting parts which are clearly set forth in the accompanying. drawings and described in the specification, and the essential featuresof which will be summarized in theappended claims.

In the drawings,

Fig. 1 is a side elevational view of a lathe Fig..2is a top plan View, enlarged, of a portion of the lathe of. Fig. 1; f

Fig.'3'is a transverse sectional View further enlarged' and taken along the line. 3 -'3 of Fig. 2;

Figs. 1, 5, and 6 are fragmental plan views taken near the central bottomjportion of Fig 2 and generally along the. line indicated at 44 of Fig. 3; while s a Fig. 7 is a fragmental sectional View taken along the line 1-,-'| of Fig. 3.

I have chosen to illustrate my invention as, applied .to a lathe known by the trade name of South Bend, although it will be understood by those skilled in the art. that my invention has other applicationsand is not limited solely to the device shown. In making certain cuts on a work piece. rotatably mounted in the (head: [l of the lathe it, it is sometimes desirableto move. the

cutting tool; [2 alonga cut lengthwise oithework piece, which cut is requiredto. be; stopped. atla predetermined point. It is almost impossible to manually withdraw the tool l2 away from the work piece at the end: of; such a cut and do this at the same point when progressively deeperrcuts are made} 'Ihave'providedvery sweatpants for accomplishing this result; I believe this apparatus may-be used'to-make straight, cuts up to a shoulder, but I have found it..particularly useful .incutting athread which is required to end at a certain point; and I' shall describe my invention as applied to such a device.

The lathe i0 is provided with a bed 13 having the usual ways [3a along which travels a carriage or saddle l,4' lengthwise or thebed; On 'thiscarriage is mountedja cross slide I5 which ashere' shown, is a compound slide of known ,type. The usual screw for moving the slide I 5 and" control handiwheel therefor has been re,- moved and other parts substituted therefor as will presently appear. Mounted on' the slide is the tool rest l6" which carries the cutting tool I 2. Thedepth of' cutis regulated by the knurled wheel Hintheusual manner. The carriage i4 is moved along the-lathe bed toward. and: away ifromit'he' work by the usual rack-l-8 and a pinion (not shown) controlled; by the" handwheclflltl, asis'usual. For threa'dcutting, the usual lead screw 28 is provided rotated bymeans (not shown) connected with thegear box 2i. The carriage I4 is locked'to the. lead: screw by a split nut 22 controlledby the handle 23' in the usual manner.

My improved means, for controlling the position of the; cutting tool |21comprises a pair of coacting abutments fl and-'25 which in one relativeposition'hold the tool nearerthe work piece and-inanother position permit the-tool to move "farther awayfrom thework piece. The abutment- 24 is fastened to thecarriage M by means 'of the cap screws 24a; The abutment 25, as clearlyishown in Fig; 3'', has a dovetail connection "2512; with ablock 26" which is fastened to the slide [5 by means of the screws 21. In' this manner the abutment-251s mounted on the slide 15 for sliding movement generally parallel to the longitudinal dimension of the lathe bed i3. 'Atthe right-hand end ofthe abutment 25; as viewed in Figs. 25.4; 5., and 6; is'provided. a small compression springxz't'which is heldxbetween the end o t-the abutment. 25' and a bracket 29 which is-fastened .to the slide. [5 by the cap screw 30. Small' recesses in the parts 25 and 2.9,. hold the spring 28: in place. Themovement of abutment 25' toward the lef (as viewed in thesesame figs.) may be limited; ifldesired. by'means of. the stop member 3 l fastened to "the block 25'.

. 7 For controllinga thread cutting. operation or for cuttingup-to asharp shouldenl provide the iform oi abutment. shown in Figs. 2; 4, 5, and '6 whereimsharp-shoulders15b and 24b, are provided. on. .the respective abutments, these shoulders extending substantially at right angles to. the long dimension of. the lathe bed. With this. arrangement, when the shoulder portions are- Iapping,. as. shown in Fig-.. 6,. theslide. I5. is held. toward. the, top. of. the. sheet as viewedv in Fig. 2 that is,. in a. position. to.- hold'the tool 12 nearer the work piece 32 which is, mounted in this case in a chuck in the lheadstock. When theseshoulder. portions. are in: the full line position of.,Figs. 2,.4-,.and. 5,,it.is then possible for the slide IE to move farther toward the bottom of the sheet, as viewed in Fig. 2, or in a direction 3 to cause the tool l2 to move away from the work piece 32.

The slide I5 is held as far toward the abutment 24 as possible at all times during a cutting operation by means of spring 33, best seen in Figs. 2, 3,

and '7. This spring is held between bracket 34 on the slide I5 and bracket 35 on the carriage M. The spring surrounds the link 36 which is connected between bracket 34 and the lower end of. handle 31 which is pivotally connected to the bracket 35 at the point 31a. The link 36 is adjustable by means of the nut 38, and the stroke of handle 31 may be limited, if desired, by means of the adjusting screw 39 carried by plate I511. bolted to the rear end of the slide [5.

It results from the above-described construction that the spring 33 normally urges the slide l5 toward the left, as Viewed in Fig. 3, or toward the bottom of the sheet, as viewed in Fig. 2. If the tool I2 is cutting a thread on the work piece 32 from right to left, as viewed in Fig. 2, the abutments 24 and 25 are placed in the relative position of Fig. 6 by moving the handle 31 from the full line position of Fig. 3 to the dot-dash line thereof whichmoves the slide to the position shown in Fig. 5. This carries the block and the abutment 25 to a position where the shoulders 25b and 24b are clear of each other, asshown in Fig.5. At this time, the spring 28 will move the abutment 25 from the full line position of Fig. 5 to the dot-dash position there shown against the stop 3|. If the carriage I4 is now locked to the lead screw 20, by manipulation of the handle 23 the tool l2 will be carried from right to left to cut the thread 32a on the end of the work piece 32.

Means is provided to cause the tool l2 to jump out of the work suddenly when it has reached the end of the thread-cutting operation. This means comprises a stop 40 adjustably mounted by set screw 4| in a bracket 42 fixed to an immovable portion of the lathe. The end of stop 40 is positioned opposite the left end of abutment 25 as viewed in Figs. 2, 4, 5, and 6 and in a different plane from the stop pin 3|. It results from this construction that if the stop 40 is properly positioned with respect to the thread-cutting operation at 32a, it will engage the end of abutment 25 as carriage I4 moves toward the left (Fig. 2) holding the abutment 25 stationary while the abutment 24 continues to travel in the same direction as previously. This causes the relative position of abutments 25 and 24 to change from that shown in Fig. 6 to a position where the shoulders 25b and 241) are in registration at which time the spring 33 causes these abutments to nest together, as shown in Fig. 4, which causes the tool I2 to jump suddenly out of the work piece 32.

While I have-shown my device used to control a cut made in one direction along the length of the lathe bed, it will be obvious to those skilled in this art how the same may be applied to control a cut made in the opposite direction. Likewise, while I have described the cutting of a thread, it is obvious that by properly regulating the tool l2 and the feed applied thereto that a smooth out might be made up to a predetermined point where the stop 40 would cause the tool to jump away from the workpiece. Other uses for my invention will be readily apparent to those skilled in this art.

What I claim is:

1. Support means for a lathe tool comprising a carriage movable along the lathe bed, a two-part slide mounted on said carriage for movement transversely of the lathe bed, said slide having a movable part and a relatively fixed part, a tool carried by said movable slide part, a spring between said slide parts urging said movable part in one direction to move said tool away from a work piece, two coacting abutments limiting movement of said movable slide part in said one direction, one of said abutments being mounted on said fixed slide part, the second of said abutments being mounted adjacent the first named abutment and on said movable slide part for movement generally longitudinally of the lathe bed, said abutments having a single pair of coacting sharp shoulders extending transversely of the lathe bed, said abutments having one relative position where said shoulders overlap to hold said tool nearer the work piece, said abutments having another relative position where said shoulders nest to permit said tool to move farther from the work piece under the influence of said spring, and means fixed relative to said lathe bed adapted to engage said second abutment as said carriage moves along said bed in such a manner as to cause relative movement of said abutments from overlapping position to nesting position.

2. Support means for a lathe tool comprising a carriage movable along the lathe bed, a twopart slide mounted on said carriage for movement transversely of the lathe bed, said slide having a movable part and a relatively fixed part, a tool carried by said movable slide part, a spring between said slide parts urging said movable part in one direction to move said tool away from a work piece, two coacting abutments limiting movement of said movable slide part in said one direction, one of said abutments being mounted on said fixed slide part, the second of said abutments being mounted adjacent the first named abutment and on said movable slide part for movement generally longitudinally of the lathe bed, said abutments having sharp shoulders extending transversely of the lathe bed, said abutments having one relative position where said shoulders overlap to hold said tool nearer the work piece, said abutments having another relative position where said shoulders nest to permit said tool to move farther from the work piece under the influence of said spring, means fixed relative to said lathe bed adapted to engage said second abutment as said carriage move along said bed in such a manner as to cause relative movement of said abutments from overlapping position to nesting position, a spring urging said second abutment toward said overlapping position, said second named spring being so constructed and arranged that it is loaded upon engagement of said second abutment by said fixed means, and means for moving said movable slide part in the other direction against the force of said first named spring to separate said shoulders and to permit said second named spring to act.

STANLEY C. MACK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

